92 FLORIDA GEOLOGICAL SURVEY-EIGHTH ANNUAL REPORT. 
the dividing line between the Oligocene and the Miocene. The 
species, however, which show the advanced development similar 
to that of the Florida species, are those characteristic of the Mio¬ 
cene. The genus Oxydactylus, to which the Florida camel is provi¬ 
sionally referred, is known only in the Miocene. The genus 
Mesocyoh, to which the canid is provisionally referred, is known 
from the John Day formation, although the Florida canid repre¬ 
sents probably a more advanced species than those of the John Day 
beds. It would seem, therefore, as a whole, that the vertebrate fos¬ 
sils indicate that the Alum Bluff formation is to be referred to the 
Miocene. The presence of the protohippine horses in particular 
would seem to be decisive as to the age of the formation excluding 
its reference to the Oligocene. 
On the basis of the invertebrate fauna, Maury correlates the 
Chipola marl at the base of the section at Alum Bluff with the 
Aquitanian of Europe, while the overlying sands of the Alum Bluff 
formation are placed as transitional.f 
The flora of this formation is known, the fossil plants found 
at Alum Bluff having been described by E. W. Berry. t Although 
consisting largely of new species, the flora according to Berry finds 
its relationship with the Aquitanian (Miocene or transitional from 
the Oligocene to the Miocene, or with the next succeeding stage, 
the Burdigalian of Europe. 
It appears, therefore, that the evidence derived from the flora 
is not necessarily greatly at variance with that afforded by the ver¬ 
tebrates. The invertebrates known from the fuller's earth horizon 
of the Alum Bluff formation are not numerous, and when addi¬ 
tional species shall have been obtained, the evidence of the inverte¬ 
brate fauna possibly will not conflict with that of the vertebrate 
fossils. 
PLIOCENE OR UPPER MIOCENE. 
The marine Miocene is well developed in Florida, being repre¬ 
sented in West Florida by the Choctawhatchee marl and in East 
Florida by the Jacksonville formation. The Choctawhatchee marl 
contains an abundance of marine invertebrates, from which the age 
of the formation has been definitely determined. The Jacksonville 
t A Comparison of the Oligocene of Western Europe and the Southern Unit¬ 
ed States. By Carlotta Joaquina Maury, Bulls, of Amer. Paleontology, Vol. 3, 
No. 15, 1902. 
+ U. S. Geol. Surv., Professional Paper 98, E., p. 44, 1916. 
